This invention relates to systems for handling mixed mail and related flat articles, and more particularly to a follower mechanism adapted for feeding such articles to a singulation head or other processing mechanism.
When articles, such as mixed mail, are received at a processing location, they must be initially organized in a manner so that they may be sorted or otherwise processed. In many cases, this involves manually stacking the mail or other articles on a feeder machine which delivers the articles to a singulation head or other suitable processing apparatus. Frequently, the feeding machine is the sole interface with a human operator in the entire mail/article processing system, at least until processing of the articles has been completed and they are ready to be removed. Therefore, it is particularly important that this portion of the machine be both safe and accommodating to the ergonomic needs of the operators.
Feeder machines for mixed mail typically include some type of follower mechanism, the operator forming a stack of mail between the follower mechanism and, for example, a singulation head of a mail processing machine. The follower then operates, generally in conjunction with a drive belt, to deliver the mail stack to the singulation head, while maintaining a desired orientation for the stack and a desired pressure for the lead piece of mail on the stack against the singulation head. An example of a system of the type indicated above is shown in co-pending application Ser. No. 09/411,961, filed Oct. 4, 1999; a mechanism for controlling orientation of the stack and pressure of the stack against a singulation head in such a system is disclosed in co-pending application Ser. No. 09/499,184, filed Sep. 23, 1999. The subject matter of these two prior-filed application is incorporated herein by reference.
In any such system where mail or other flat articles are being manually stacked in front of a follower, which follower is drivable to feed the articles, either alone or in combination with other drive mechanisms, the follower, along with its retracting, driving and linear guidance components, should be designed so as to be as easy, comfortable and safe for the operator to use as possible. Ease and comfort of use in particular can facilitate more rapid loading of the system by the operator, the time required for the operator to load the mail onto the feeding machine being one of the limitations on through-put for such machines. Durability and maintainability are other important criteria.
Unfortunately, many existing feeder machines are dangerous for operators, are unreliable and are maintenance intensive. They can also be awkward to load, particularly where is necessary to either load a fixed amount of mail (too few or too many mail items causing reliability problems), or to use one hand to serve as a temporary follower during the loading operation. A need therefore exists for an improved follower mechanism with enhanced ease, comfort and safety for the operator, as well as enhanced reliability and durability.
In accordance with the above, this invention provides a follower mechanism for use in an system for feeding flat articles, such as mixed mail, in a selected direction. The follower mechanism includes a paddle assembly; a mount to which the paddle assembly is pivotably connected, the paddle assembly being pivotable on its mount between a feed position and an inactive position; a guide connected to the mount, the guide facilitating movement of the mount only forward and backward in the selected direction; a drive providing controlled movement in the selected direction; and a mechanism connecting the mount to be driven forward in the selected direction by the drive, while inhibiting backward movement of the mount when the paddle assembly is in its feed position, the mechanism permitting the mount to be freely moved forward and backward when the paddle assembly is in its inactive position. The follower mechanism preferably includes a counterbalance mechanism which controls pivot movement of the paddle assembly between its two positions, the counterbalance mechanism applying a force to the paddle assembly which assists in raising the paddle assembly from its feed to its inactive position and partially supports the weight of the paddle assembly when the paddle assembly is lowered from its inactive to its feed position. For preferred embodiments, the counterbalance mechanism includes a compression spring mechanism positioned in the mount. The counterbalance mechanism preferably exerts greatest force on the paddle assembly when the paddle assembly is in its feed position.
For preferred embodiments, the mechanism connecting the mount to the driver includes a slide member normally biased to a raised position, by for example the counterbalance mechanism, the slide member interacting with the paddle assembly, starting at a point in the movement of the paddle assembly between its inactive and feed positions, to move the slide downward towards the drive; the slide member includes a component at the bottom thereof which engages the drive when the paddle assembly has reached its feed position. For preferred embodiments, the drive is a chain drive, and the component at the bottom of the slide member which engages the drive is a pawl. The pawl is preferably shaped to prevent disengagement of the pawl from the chain as a result of back pressure applied to the paddle assembly. A mechanism is preferably provided which is operative in response to the paddle assembly being moved from its feed to its inactive position for positively disengaging the pawl from the chain. For a preferred embodiment, this disengagement mechanism includes a hook on the slide and a pin on the paddle assembly, the pin being engaged by the hook during portions of pivot movement of the paddle assembly which are in a direction substantially perpendicular to the chain. Where positive disengagement of the pawl from the chain is provided, a hold-down member is preferably provided for the chain, the hold-member facilitating disengagement of the pawl from the chain. For preferred embodiments, the hold-down member is attached to the mount for the paddle assembly. The mechanism for connecting the mount to the drive preferably causes the pawl to be moved substantially perpendicular to the chain during engagement and disengagement of the pawl and chain. For preferred embodiments, the guide is a bearing. For some embodiments, the counterbalance mechanism may be utilized independent of the particular mechanism for connecting the slide member to the drive, although these two features are preferably utilized together.
The foregoing and other objects, features and advantages of the invention will be apparent from a following more particular description of an illustrative embodiment as shown in the accompanied drawings, the same reference numerals being used for common elements in the various figures.